Spray-type absorption tower



P 25, 1951 F. WETHLY ET AL 2,568,875

SPRAY-TYPE ABSORPTION TOWER Filed July 20, 1949 2 Sheets-Sheet 1 FIGJ. i

INVENTORS. 'FRANS WETHLY LEONHARD T. HARTMANN ATTO NEY.

Patented Sept. 25, 1951 SPRAY-TYPE ABSORPTION TOWER Frans Wethly, Manhasset, and Leonhard T. Hartmann, New York, N. Y., assignors to Allied Chemical & Dye Corporation, New York, N. Y., a corporation of New York Application July 20, 1949, Serial No. 105,862

3 Claims. (Cl. 261111) This invention relates to gas and liquid contact apparatus and more particularly refers to a new and improved spray-type tower for contactting gas with liquid especially adaptable for cooling of coke oven gas or absorption of coke oven gas constituents such as ammonia and light oil.

Gas-liquid contact devices utilizing packing, bubble-cap trays, perforated plates and baflles have been employed with varying degrees of success. These devices have one or more drawbacks including large bulky construction, reduced capacity due to low space efficiency, high investment cost, frequent plugging of apparatus, channelling, and of especial significance to the coke oven gas industry, substantial resistance to the flow of fluids. Resort was had in some instances to towers wherein liquid introduced into the top was sprayed downwardly countercurrent to a rising stream of gases entering the bottom. While these towers appreciably lowered the pressure drop, unfortunately, due to the long path traversed b the dropping liquid, stratification of the liquor occurred resulting in unequal distribution and poor contact with the gas thereby lowering the efiiciency of operation. Better contact but not distribution of liquid may be obtained by the introduction of excessively large amounts of liquid at, of course, a sacrifice in dilution of the liquid product and increased operating costs. Some improvement has been made on the spraytype device by the insertion of a plurality of sprays, each equipped with piping, pumps and control means for mechanically forcing the liquid from one to another. The addition of this auxiliary equipment materially increases the cost of the apparatus and complicates the operation by the requirement of manipulating the multitude of controls; therefore, in the coke-oven industry devices of this type are of infrequent occurrence. Also, as in the case of treating coke oven products, the fluids frequently contain suspended solids which cause considerable difliculty from'clogging or wearing out of the pumps or other portions of the apparatus because of corrosion and abra- SlOIl.

An object of the present invention is to provide a spray-type tower of economical construction adapted to effect repeated redistribution of liquid and maximum intimate contact between gas and liquid with low and uniform pressure drop in the tower.

Another object of the invention is to provide a spray-type tower of high efliciency with greater capacity having a simple construction to avoid the possibility of defective working.

A further object of the invention isto provide a tower wherein liquid is sprayed by gravity through successive spray units in the contact equipment, substituting initial elevation for the normally required pumping.

A still further object is to provide a new and improved gravity spray unit in absorption or cooling tower equipment.

Further objects and advantages will be apparent from the following description and accompanying drawings.

In accordance with the present invention we provide an improved absorption and cooling tower which is especially adapted for the separation and treatment of constituents in coke oven gas. In operation, gas introduced into the bottom of the tower passes upwardly countercurrent to a plurality of sprays of liquid; the scrubbed or cooled gas then discharges through the top of the tower and accumulated liquid is removed from the bottom of the tower.

A feature of the present invention resides in means spaced along the height of the tower for collecting pools of liquid of sufficient head to cause the liquid to discharge in the form of a spray from nozzles disposed beneath the pools. In this manner gravity is utilized for redistribution of the absorbing liquid in the tower thereby elminating pumps, pipes and controls normally required for this purpose. With the increased cost of packing and the difficulties involved in cleaning all types of packing in conventional tower scrubbers the scrubber of the present invention is of particular value because packing is eliminated and the non-plugging, low gravity head spray means used for redistribution of the absorbing liquor eliminates the piping usually required for such distribution.

In one embodiment of the invention the apparatus comprises a vertical cylindrical casing having a gas inlet and a liquid outlet near the bottom and a liquid 'inlet and a gas outlet near the top, a plurality of spaced liquid spray units disposed along the height of the cylindrical chamber, each spray unit consisting of a circular plate divided into two segments with the chords of the two segments joined to a central trough for the collection of liquid falling from above on the segments inclined toward the trough, a pipe terminating in a spray nozzle connected to the bottom of the trough, a semi-circular hole in each segment on each side of the trough to permit the free passage of gas upwardly through the segments, a vertical lip extending along the arc of the semi-circular holes to prevent the flow of 3 liquid therethrough, an inverted cup-shaped baflle disposed above the two semi-circular holes to prevent liquid from falling through the semicircular holes, and side openings in the inverted cup-shaped bailles for the escape of gases passing through the semi-circular holes.

Referring to the drawings:

Figure 1 is a vertical sectional view with portions cut away of the spray-type absorption tower embodying the present invention.

Figure 2 is a fragmentary elevation in section showing a spray unit of the absorption tower on a larger scale.

Figure 3 is a perspective view of a spray unit of the absorption tower with the inverted cupshaped bailie removed.

Referring to Figure l, the tower comprises a vertical cylindrical shell or casing I having a gas inlet 2 through which gas enters disposed below the spray means, and a gas outlet 3 near the top through which gas discharges. Liquid absorption media introduced through conduit 4 collects in a pool of sufficient head on spray unit 5 to discharge by gravity through spray nozzle 6. The absorption media distributed by means of spray nozzle 6 in the form of finely divided particles or mist across the cross-sectional area of easing I, falls upon a succeeding spray unit 5, collects in a pool therein and discharges by gravity through a succeeding spray nozzle 6. The lowermost unit 5 instead of terminating in a spray nozzle 5 has substituted a downpipe i from which the liquid flows, accumulates in the bottom of the tower i and withdrawn through liquid outlet 8. As indicated in Figure 1 a multiplicity of spray units 5 may be employed depending, oi 01 course, upon the process requirements. Casing I may be provided with conventional windows and manholes, not shown in the drawing, for visibility and ready access into the tower. All the spray units 5 in tower i are of similar construetion but desirably are staggered with their troughs at right angles to one another as shown in Figure 1. In order to insure the maintenance of a proper liquid level in spray units 5 a gauge glass 9 connected at a point above spray unit 5 by conduit I i and to the liquid pool by conduit i2 may be provided. Adjustment of the liquid level in spray units 5 may be made by pumping more or less absorption media through liquid inlet 4.

In Figure 2 spray unit 5 is supported in position by angle irons l3. A cement seal i4 between the inner wall of casing I and the outer ends of spray unit 5 prevents leakage of gas along the walls. A circular plate consists of segments i5 which are inclined towards the trough which latter is bounded by end walls l6, side walls I! and bottom l8. A cover plate l9 attached to side walls I! of the trough facilitates gas distribution and prevents liquid from spilling out at this point. Covering the semi-circular holes 2! in segments I5 is an inverted cup-shaped baffle 22, preferably of decreasing diameter and having side openings 23 for the escape of gases passing therethrough. Extending from bottom i8 of the trough is downpipe 24 terminating in spray nozzle 6. Although any suitable spraying means may be adopted for effecting the dispersion of liquid in fine droplets across the cross-sectional area, we have found a spray nozzle consisting of several spaced convex plates 25 of diminishing size joined together by members 25 and having central conduits 21 of diminishing diameter through the several plates gives a series of curtains of varying intensity so as to effectively spread the liquid droplets across 4 the cross-sectional area 01' the tower as shown by dotted lines.

The assembly of spraying unit 5 may be more readily seen in Figure 3 which for clarity has omitted baflie 22. The circular plate consisting of inclined segments I5 is disposed on an L- shaped member .28 which rests on angle iron II, as shown in Figure 2. Between the opposed segments i5 is the trough formed by end walls It, side walls. I! and bottom ll. Liquid droplets from above falling on inclined segments l5 roll into the trough, drain through tapered conduit 29, thence into pipe 24. The stream of liquid leaving the bottom 01' conduit 24 falls on the first distributing plate 25 from which a portion 01' the liquid is directed laterally across the tower in the form of a curtain of liquid. Another portion of the liquid falls through opening 21 onto the succeeding plate and a second curtain of liquid of smaller intensity is directed across the tower. In this manner nozzle 6 produces a series of liquid curtains of varying intensity across the tower. A head of liquid resulting from the pool of absorption media accumulating in the trough and pipe 24 of about 50 inches will ordinarily have suflicient pressure for the emission of sprays of desired intensity. Gases pass upwardly through spray unit 5 out of contact with the liquid by rising through semi-circular holes 2| and thence out through bailie 22 shown in Figure 2. A vertical lip 3| extends along the arc oi the semi-circular holes 2| to prevent liquid from flowing down through them. In this manner all the liquid above the spray unit is utilized to provide a gravity head for the spray nozzle immediately below. The semi-circular holes 2! should be of suillcient size so as not to appreciably retard the flow of gases therethrough. Ordinarily the operation will be satisfactory if the radius of the semi-circular hole 2| is about onequarter the radius of segment I5. As previously mentioned in connection with Figure 2 cover plate l9 attached to side wall ll of the trough shown in greater detail in Figure 3 prevents liquid from spilling out at this point.

Although certain preferred embodiments of the invention have been disclosed for purpose of illustration it will be evident that various changes and modifications may be made therein without departing from the scope and spirit of the invention.

We claim:

1. A gas and liquid contact apparatus comprising an upright casing, a gas inlet and liquid outlet near the bottom of the casing, a gas outlet and liquid inlet near the top of the casing, a plurality of spaced liquid spray units disposed along the height of the casing intermediate the gas outlet and liquid inlet near the top of the casing and the gas inlet and liquid outlet near the bottom of the casing, each spray unit comprising a plate divided into two segments with the chords of the two segments joined to a trough for the collection of liquid falling from above on the segments inclined toward the trough, a pipe terminating in a spray nozzle connected to the bottom of the trough, an aperture in each segment on each side of the'trough to permit the free passage of gas upwardly through the segments, and a baille disposed above the apertures to prevent liquid from falling therethrough.

and liquid inlet near the top of the casing, a plurality of spaced liquid spray units disposed along the height of the casing intermediate the gas outlet and liquid inlet near the top of the casin and the gas inlet and liquid outlet near the bottom of the casing, each spray unit comprising a plate divided into two segments with the chords of the two segments joined to a trough for the collection of liquid falling from above on the segments inclined toward the trough, an aperture in each segment on each side of the trough to permit the free passage of gas upwardly through the segments, a baflle disposed above the apertures to prevent liquid from falling therethrough, and said spaced liquid spray unitsplaced in staggered relationship with the troughs of altemate spray units disposed at a right angle to one another.

3. A liquid spray unit adapted for use in gas and liquid contact apparatus comprising 5. circular plate divided into two segments with the chords of the two segments joined to a central trough for the collection of liquid falling on the segments inclined toward the trough, a pipe, terminating in a spray nozzle connected to the bottom of the trough, a semi-circular hole in each segment on each side of the trough to permit the tree passage of gas upwardly through the segments, a vertical lip extending along the arc of the semi-circular holes to prevent the flow of liquid therethrough, an inverted cup-shaped baflle disposed above the two semi-circular holes to prevent liquid from falling through the semi-circular holes and side openings in the inverted cupshaped baflle for the escape of gases passing through the semi-circular holes.

FRANS WETHLY.

LEONHARD T. HARTMANN.

REFERENCES CITED UNITED STATES PATENTS Number Name Date 20 965,116 Morison July 19, 1910 1,989,033 Weir Jan. 22, 1932 2,088,124 Webre July 27, 1937 FOREIGN PATENTS 26 Number Country Date 120,304 Great Britain Nov. 7, 1918 

